1. Field of the Invention
The present invention relates to a receiving antenna apparatus that receives a radio signal transmitted from a capsule endoscope inside of a subject.
2. Description of the Related Art
Conventionally, in the field of an endoscope, a capsule endoscope with a built-in imaging function and a radio communication function, which are provided in a capsule-shaped casing formed to a size that can be introduced into the gut of a subject such as a patient, is known. The capsule endoscope is first swallowed from the mouth of the subject and then it moves in the inside of the subject such as the gut by peristaltic movement and the like. Then, it sequentially captures images of the inside of the subject to generate image data, and sequentially transmits the image data.
The image data thus transmitted from the capsule endoscope by wireless transmission is received by a receiving apparatus through a receiving antenna provided outside the subject. The receiving apparatus stores the image data received through the receiving antenna in a built-in memory.
The subject can freely act during a period until the capsule endoscope is excreted after the capsule endoscope is swallowed, by carrying the receiving apparatus that has a radio communication function and a memory function. After the examination, a practitioner such as a doctor puts the image data accumulated in the memory of the receiving apparatus in an image display apparatus so that images of the inside of the subject which correspond to the images obtained by the capsule endoscope, that is, the internal organs' images are displayed on a display of the image display apparatus. The practitioner observes the images of the internal organs and the like displayed on the display, and diagnoses the subject.
In receiving the radio signal transmitted from the capsule endoscope, a typical receiving apparatus has a plurality of receiving antennas arranged in a dispersed manner outside the subject, selects one antenna with the strongest received strength, and receives the radio signal by the selected antenna. For example, there is a known receiving apparatus in which reception switching among a plurality of antennas placed outside a subject is performed and which detects the position of a capsule endoscope in the subject that is the source of a radio signal based on the field strength received by each antenna (See Japanese Patent Application Laid-open Publication No. 2003-000608).